1. Field of the Invention
This invention pertains to the motor vehicle arts, in particular to dynamic measurement of the pressure and temperature of a motor vehicle tire as a control parameter for an operational or safety function.
2. Discussion
Most modern motor vehicles operate on suspension systems which utilize pneumatic tires. Pneumatic tires can be found in a variety of constructions, such as radial ply construction or bias ply construction, and while tires most commonly have a tubeless design, there remain types which utilize a tube to maintain air pressure. Due to the pressurized air held within a pneumatic tire, the tire provides certain advantages in ride and control of a motor vehicle. The pneumatic characteristic also has an impact on the suspension design of the vehicle.
When the vehicle is in motion, and the tire is rolling over the road surface, the tire is going through a continuous and dynamic change, particularly in its shape. In a pneumatic tire, the surface of the tire touching the road is compressed while the remaining majority portion of the tire resides in a normal state. The continual fluctuation as the tire rolls over the road caused by compression of a portion of the tire's surface, causes the tire and the air compressed within it to increase in temperature. Additionally, depending upon the maneuver that the vehicle is going through or the toughness of the surface over which the tire is rolling, the pressure of air within the tire may vary. For instance, increased load within the vehicle will increase the pressure within all of the vehicle's tires. Cornering the vehicle will increase pressure in the tires of the vehicle on the outside of the turn. Dynamic operation of the tire, which is mounted to the vehicle's suspension system, causes pressure variations, such as would occur when the tire rolls over a rough or washboard-like surface, or hits a bump. Many studies have been done by tire companies to investigate tire temperature and pressure changes in order to improve tire design characteristics.
With the advent of modern electronics, which are durable and require low power, applications of electronic systems in motor vehicles have been significantly increasing. Electronics now control most fuel management and ignition systems for engines powering motor vehicles. Automatic brake systems which assure that a wheel and tire will not skid in inclement weather or under severe braking conditions have been introduced. Electronic control of the damping elements of the vehicle suspension system, i.e., the shock absorbers, has also been designed and implemented, permitting a driver to vary the ride control of the suspension from within the driving compartment through manual selection of increased or decreased damping characteristics.
Since the ride and control of the motor vehicle is intimately dependent upon the characteristics of its suspension system, improvements in suspension system design are continually sought. Through the use of modern electronics, active control of the damping characteristics of a vehicle's suspension system has been suggested. Other parameters of suspension system design may also be dynamically controlled, such as, spring rate or roll stabilizer control.
The unfulfilled need in such an active control system is development of an accurate, but consistent and reliable means for determining control of such a suspension system. This is perhaps the primary and most important element in active suspension design. In order for a dynamically controlled suspension system in a motor vehicle to be effective, it must have suitable means by which the control required can be determined. It is believed that the invention presented herein will fulfill this need and provide an accurate, consistent, and reliable means for directing a dynamically controlled suspension system in a motor vehicle.
The present invention utilizes tire pressure and/or temperature as a source of information for a vehicle suspension system control. The following discussion of hardware is merely one example which would work but various other designs and hardware could be used to obtain the same effect.